Let's do some math.

If we take a look what's inside the bracket it's 8/3 + 13/2 - 25/6 which can be substituted with 16/6 + 39/6 - 25/6 which equals 30/6 = 5
The square root of 4 is 2 and 5 in the power of 2 equals to 25

So now we have the following equation in the brackets
(25 - 2 ^ n)

n goes from 2 to 6 so the equation will be taken 5 times, we can pull out the constant out of the equation 25 * 5 = 125
So now we have
125 + 6Σn=2 -2^n
2^n will equate in 4,8,16,32,64
So if we add them up we get 124 and all we have to do is to subtract it from 125 which will equal 125 - 124 = 1, which isn't 1+1
So in other words, Cirno is a ⑨

Expanda90 said:

Let's do some math.

-space-age math ensues, imo

So in other words, Cirno is a ⑨

This is why i like Danbooru's comment section.